How to use scalebox in captions? [duplicate]

Question

This code:

\documentclass[a4paper,twoside,12pt]{scrreprt}
\usepackage{fontspec}
\begin{document}
Test \scalebox{3.0}{$\int$} test.
\begin{table}
  \centering
\begin{tabular}{cc}
  A & B \\
  C & D 
\end{tabular}
\caption{Test \scalebox{3.0}{$\int$} test.}
\end{table}
\end{document}

gives me the error message:

! Argument of \@caption has an extra }.

The result looks how I want it to, though...

What should I do?

Answer 1

You have two options. First one is to \protect \scalebox:

\documentclass[a4paper,twoside,12pt]{scrreprt}
\usepackage{graphicx}
%\usepackage{fontspec}
\begin{document}
Test \scalebox{3.0}{$\int$} test.
\begin{table}
  \centering
\begin{tabular}{cc}
  A & B \\
  C & D
\end{tabular}
\caption{Test \protect\scalebox{3.0}{$\int$} test.}
\end{table}
\end{document}

Second one is to use the optional argument of \caption:

\documentclass[a4paper,twoside,12pt]{scrreprt}
\usepackage{graphicx}
%\usepackage{fontspec}
\begin{document}
Test \scalebox{3.0}{$\int$} test.
\begin{table}
  \centering
\begin{tabular}{cc}
  A & B \\
  C & D
\end{tabular}
\caption[Test $\int$ test.]{Test \scalebox{3.0}{$\int$} test.}
\end{table}
\end{document}

This happens as the contents of \caption are movable (i.e., fragile) as they may be used in lof and you have to \protect commands (from expanding) used inside the argument.